Field of the Invention
Embodiments of the present invention generally relate to improved structured light depth imaging under various lighting conditions.
Description of the Related Art
In structured light imaging systems, a projector-camera pair is used to estimate the three-dimensional (3D) depth of a scene and shape of objects in the scene. The principle behind structured light imaging is to project patterns on objects/scenes of interest and capture images with the projected pattern. The depth is estimated based on variations of the pattern in the captured image in comparison to the projected pattern.
Many real-time structured light imaging systems use a binary projection pattern. To generate 3D images using visible structured light patterns, the images are captured in a dark room with very little interfering light. The signal-to-noise ratio (SNR) in such scenarios is very high. A second alternative is to use infrared (IR) structured light patterns and use sensors with notch filters tuned to the particular wavelength of the projected infrared (IR) pattern. This setup filters out a majority of the interfering ambient light to increase the SNR, thus allowing the imaging system to be used indoors with some ambient light.
But current IR projection pattern based techniques will fail in presence of bright interfering light with a matching IR frequency component. For example, real-time structured light devices such as Microsoft Kinect fail in the presence of bright interfering light such as sunlight coming through a window into the room where the device is being used. Sunlight contains light of all frequencies and thus has some interfering light which matches the wavelength of the projected pattern. Further, the optical properties of the objects present in the scene also influence the quality of the pattern observed by the camera, e.g., white objects reflect more light than black objects.